Step by step recipe:

1. 5 min.
   Pour 750 ml liquid cream, 30 ml Brandy (Cognac or Armagnac) and 30 ml Port into a pan on low heat. Add 4.5 g salt, 1.5 g pepper, 3 pinches "Quatre-épices" spice blend and 375 g raw foie gras cut into pieces.
   
   Heat gently until the foie gras has completely melted.
2. 5 min.
   Blend the mixture thoroughly and check seasoning.
3. 5 min.
   Strain the resulting liquid through a sieve. Clean the pan and pour the liquid back into it.
4. 5 min.
   Add 6 egg yolks and beat thoroughly to mix well.
5. 3 min.
   Blend again briefly if necessary.
   
   Preheat the oven to 110°C (240°F).
6. 30 min.
   Divide the mixture between the ramekins and put in the oven in a bain-marie (as for a crème brulée).
7. 2 hours
   As soon as the creams are cooked, remove from the oven and leave to cool to room temperature, then refrigerate for at least 2 hours.
   
   The preparation and cooking to this stage can be done in advance, even 1 or 2 days beforehand.
8. 15 min.
   Peel and rinse the potatoes, then cut into thick slices.
   
   Boil in salted water until soft.
   
   You will need 390 g potatoes after cooking.
9. 5 min.
   Pour 210 ml liquid cream into a pan on low heat with 210 ml milk, 60 g butter and the cooked potatoes.
   
   Bring to the boil, then blend thoroughly.
   
   Check seasoning.
10. 10 min.
    Pass the potato cream mixture through a sieve or fine strainer, then pour into a cream whipper.
    
    Pierce 2 gas cartridges and shake well.
    
    Note: if you have a basic cream whipper (i.e. not insulated), wrap it in a tea towel, or you risk burning yourself as the contents will be very hot.
11. 5 min.
    Make the crispy ham by frying morsels of serrano in a very hot frying pan without any added fat. fry on both sides until crisp.
12. 5 min.
    Assemble the creams: to each ramekin (they should be really cold), add a layer of hot espuma of potato and stick 2 pieces of ham into the top.
    
    Serve immediately.